Sodium Chloride Crystal CleavageA knife is placed on a large sodium chloride crystal parallel to a cleavage plane. When the knife is tapped, the crystal breaks cleanly, creating two smaller crystals.

Crystals / Crystallography |

Ionic Bonding |

Solids

Plastic SulfurYellow powdered sulfur is heated until it becomes molten and brown. At first it flows freely, but then it becomes very viscous. Upon further heating, the viscous sulfur flows freely again and ignites. The burning liquid sulfur is poured into a beaker of water. When removed from the water, the sulfur is rubbery and flexible.

Hardness of Solid Substances - GrindingA number of metals and nonmetals are ground with a mortar and pestle. The nonmetals shown here are all soft (due to weak intermolecular forces), but the metals vary in hardness.

Covalent Bonding |

Nonmetals |

Physical Properties |

Solids |

Metallic Bonding |

Metals

Thermochromism: Mercury(II) IodideWhen red-orange Mercury(II) Iodide (HgI2) is heated, it undergoes a phase transition at 126oC to a pale yellow form. As the heated sample cools, it gradually returns to the original red-orange color.

Crystals / Crystallography |

Phases / Phase Transitions / Diagrams |

Physical Properties |

Solid State Chemistry |

Solids |

Descriptive Chemistry

SolutionsReactions and demonstrations exploring the concepts of solutions.